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message_buffer.c    57 lines (43 with data), 1.1 kB

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/* -*- c-basic-offset: 4 -*- vi:set ts=8 sts=4 sw=4: */
/* message_buffer.c
This file is in the public domain.
*/
#include <unistd.h>
#include <string.h>
#include <pthread.h>
#include <stdio.h>
#define BUFFERS 16 /* must be 2^n */
#define BUFFER_SIZE 256
static char buffer[BUFFERS][BUFFER_SIZE];
static const char *mb_prefix;
static unsigned int initialised = 0;
static unsigned int in_buffer = 0;
static unsigned int out_buffer = 0;
static pthread_t writer_thread;
void *mb_thread_func(void *arg);
void add_message(const char *msg)
{
strncpy(buffer[in_buffer], msg, BUFFER_SIZE - 1);
in_buffer = (in_buffer + 1) & (BUFFERS - 1);
}
void mb_init(const char *prefix)
{
if (initialised) {
return;
}
mb_prefix = prefix;
pthread_create(&writer_thread, NULL, &mb_thread_func, NULL);
initialised = 1;
}
void *mb_thread_func(void *arg)
{
while (1) {
while (out_buffer != in_buffer) {
printf("%s%s", mb_prefix, buffer[out_buffer]);
out_buffer = (out_buffer + 1) & (BUFFERS - 1);
}
usleep(1000);
}
return NULL;
}
/* vi:set ts=8 sts=4 sw=4: */